Lower thread adjusting apparatus in sewing machines



1962 TOMIO FUKUSHIMA 3,050,021

LOWER THREAD ADJUSTING APPARATUS IN SEWING MACHINES Filed Feb. 1, 1960 5Sheets-Sheet 1 mNaVvra Tam/0 FUK H 1, 1962 TOMIO FUKUSHIMA 3,050,021

LOWER THREAD ADJUSTING APPARATUS IN SEWING MACHINES Filed Feb. 1, 1960 5Sheets-Sheet 2 Aug. 21, 1962 TOMIO FUKUSHIMA LOWER THREAD ADJUSTINGAPPARATUS IN SEWING MACHINES 5 Sheets-Sheet 3 Filed Feb. 1, 1960 Aug.21, 1962 TOMlO FUKUSHIMA 3,050,021

LOWER THREAD ADJUSTING APPARATUS IN SEWING MACHINES Filed Feb. 1, 1960 5Sheets-Sheet 4 /Q l m 1 t J Z2 47 Z 2 30 27 //Y rs/v n K 70 mm Fum/ H/MAAug. 21, 1962 TOMlO FUKUSHIMA LOWER THREAD ADJUSTING APPARATUS IN SEWING MACHINES 5 Sheets-Sheet 5 Filed Feb. 1, 1960 IIIIIIIIII UnitedStates Patent 3,050,021 LOWER THREAD ADJUSTING APPARATUS IN SEWING MACIMES Tomio Fukushima, Osaka City, Japan, assignor to Kabushiki KaishaTohoku Kosakusho, akai City, Japan Filed Feb. 1, 1960, Ser. No. 5,932 6Ciaims. (Cl. 112-229) This invention relates to a lower thread adjustingapparatus in a sewing machine.

In a known sewing machine, it takes much trouble to adjust the tensionof the lower thread; taking out the bobbin case from the shuttle or ifit cannot be taken out, putting a screw driver into the back of themachine, to turn the adjusting screw.

The object of the present invention is to provide means to turn theadjusting screw without these troubles.

With this object in view the present invention provides a lower threadadjusting apparatus in a sewing machine wherein by working a knobinstalled at some proper place of the machine, the adjusting screw canbe turned through a remote operation mechanism with the bobbin case laidas it is in the shuttle.

Other and the further objects of the present invention will becomeapparent from the following specification and claims taken together withthe accompanying drawings in which is shown the preferred embodiment ofthe lower thread adjusting apparatus in a sewing machine according tothe present invention.

FIG. 1 is a plan view of a lower thread adjusting apparatus for ahorizontal rotation shuttle type sewing machine according to the presentinvention.

FIG. 2 is an elevation view of FIG. 1.

FIG. 3 is a sectional side view of FIG. 2.

FIG. 4 is an underside view partly in section of a lower threadadjusting apparatus for a vertical semi-circular rotation shuttle typesewing machine according to the present invention.

FIG. 5 is a sectional side view of FIG. 4.

FIG. 6 is an elevation view of FIG. 4.

FIG. 7 is an elevation View of a shuttle driver shown in FIG. 6.

FIG. 8 is an elevation view of a cam.

FIG. 9 is a sectional elevation of a lower thread adjusting apparatusfor a vertical full revolution type sewing machine according to thepresent invention.

FIG. 10 is an elevation View of a bobbin case shown in FIG. 9.

FIG. 11 is a side view of FIG. 10.

FIG. 12 is a sectional side view of FIG. 10.

FIG. 13 is an enlarged sectional view of a part of FIG. 10.

FIG. 14 is a perspective view of a bobbin case.

In FIGS. 1, 2 and 3 reference numeral 21 indicates a bobbin case set ina shuttle. A thread wound on a bobbin in the bobbin case 21 is pressedby a thread press spring 22, of which the pressing force is adjusted byan adjusting screw 23. In a frame 24 fixed on the underside of a bed 25is rotatably and slidably mounted a driving rod 26 provided with apinion 27 on one end and screw engaging blades on the other end and keptapart from the adjusting screw 23 by a spring 28. On supporters 29, 29fixed on the underside of the bed 25 is mounted a rack 30 meshed withthe pinion 27. A shaft 31 of a knob 32 is passed through a rotatablecylinder 33 fitted in a frame 34 fixed on the underside of the bed 25,provided with a spring 35. A pin 36 screwed through the side-wall of theknob 32 fits in a vertical guide way 37 cut on the side wall of thecylinder 33. A pinion 38 furnished on the lower part of the cylinder 33is meshed with the rack 30. At the rear end of a lever 39 supported on apin 40 fixed to the bed 25 is formed a cam 3,955,921 Patented Aug. 21,1962 41 to co-operate with the shaft 31, and the fore end of it is keptin contact with the driving rod 26. The frame 24 is provided with astopper 24 to hold the pinion 27 while the driving rod 26 is kept apartfrom the adjusting screw 23.

When the knob 32 is pushed down, the cam 41 formed on the rear end ofthe lever 39 is pushed aside by the lower end of the shaft 31, as shownin a chain line in FIG. 1, the fore end of the lever 39 pushing thedriving rod 26, of which the bladed end catches in the head of theadjusting screw 23. Then by turning the knob 32, the rotatable cylinderis rotated, the pin 36 catching in the guide way '37, and the rack 30meshed with the pinion 38 goes back and forth to turn the pinion 27 andthe driving rod 26, whereby the adjusting screw 23 turns to adjust thepressing force of the thread press spring 22.

In FIGS. 4, 5, 6, 7 and 8 is shown a lower thread adjusting apparatusfor a sewing machine of a vertical semicircular rotation shuttle typeaccording to the present invention. A bobbin case 21 is removably fittedin a shuttle 42 set in a case 43. The driving rod 26 for the adjustingscrew 23 is slidably and rotatably fitted in a hole 44 bored on the case43, supported by the frame 24. A pass Way 4-5 for the driving rod 26 iscut on a shuttle driver 46. The shaft 31 of the knob 32 is passedthrough an inclined opening 47 bored on the upper side of the bed 25 andsupported by the frame 34. The pinions 27 and 38 are meshed with thecrown gears 30, 30- mounted on both ends of a connecting rod 48. On ashaft 49 is mounted a cam 50 on which is cut a recess 51 at the positioncorresponding to the pass way 45 on the shuttle driver 46 so as toco-operate with a projection 52 formed On the lever 39.

When the projection 52 gets in the recess 51, with the pass way 45 readyto admit the driving rod 26, the knob 32 can be pushed for the bladedend of the driving rod 26 to catch in the head of the adjusting screw23, and

-by turning the knob 32 the adjusting screw 23 turns to adjust thepressing force of the thread press spring 22.

In FIGS. 9, 10, 11, 12, 13, and 14 is shown a lower thread adjustingapparatus for a sewing machine of a vertical full rotation shuttle typeaccording to the present invention. The driving rod 26 is slidably androtatably set in the hollow shaft 49, supported by the frame 24 andprovided with the pinion 27 to be turned by the crown gear 30 mounted onthe shaft 31 of the knob 32 (not shown). The end of the lever 29 to workon pushing the knob 32 is kept in contact with the rear end of thedriving rod 26. In an intermediate case 53 set in the shuttle 4-2 isfitted the cylindrical bobbin case 21 provided with a partition wall 54.An inclined thread way 55 is cut on the rear circumferential wall 56 ofthe bobbin case 21, and on its front circumferential wall 56 having anotch 57 are cut thread ways 58 and 59. At the center of the bobbin case21 is formed a cylinder 60, in which is loosely inserted the adjustingscrew 23, of which the head faces the end of the driving rod 26 and thetail is screwed in a screw hole 61 of the thread press spring 22 placedon the front wall 54. The upper part of the partition wall 54 isfurnished with a rotatable piece 62 having a projection 63 and its bentpart 64 is kept projecting through an opening 65 of the frontcircumferential wall 56 by a spring 66 and catches in an opening 67 ofthe intermediate case 53. Between the cylinder 60 and the threadadjusting screw 23 is laid a spring 68 for counteracting the pressure ofthe thread press spring 22.

In a lower thread adjusting apparatus constructed as above, the pressureof the thread press spring 22 upon the partition wall 54 can be adjustedby thrusting out the driving rod 26 and turning the adjusting screw 23,and the lower thread from the bobbin, led through the thread way 55 andthen to be taken out through the thread way 59, is adjusted in tensionwhen passing between the partition Wall 54 and the thread press spring22.

According to the present invention, a lower thread in a bobbin caseinstalled under a machine bed can be adjusted in tension at will byworking a knob furnished at some proper place on the machine, and thusthe tension of the lower thread can easily be kept best to produceexcellent goods with much efiiciency.

It is thought that the invention and its advantages will be understoodfrom the foregoing description and it is apparent that various changesmay be made in the form, constructions and arrangement of the partswithout departing from the spirit and scope of the invention orsacrificing its material advantages, the form hereinbefore described inthe drawings being merely a preferred embodiment thereof.

Having thus described my invention, what I claim and desire to secure byLetters Patent of the United States is:

l. A device for adjusting thread tension on a sewing machine bobbin inwhich the bobbin has thread tensioning means thereon, said devicecomprising an adjusting shaft adapted to be mounted on the sewingmachine adjacent the thread tensioning means for rotatable and slidablemovement longitudinally of its length and having engaging means on oneend thereof for engaging the thread tensioning means on the bobbin, afirst spring means engaging said adjusting shaft and urging saidadjusting shaft away from the bobbin, a first pinion on said adjustingshaft, an actuating shaft adapted to be mounted on the sewing machineadjacent said adjusting shaft for rotatable and slidable movement alongits length and having a second pinion thereon, said pinions beingdrivingly connected to each other, a second spring means urging saidactuating shaft longitudinally of its length toward one end thereof, anda lever pivotally mounted between said shafts and having one endengaging the other end of said adjusting shaft and having the other endengaging the other end of said actuating shaft.

2. A device as claimed in claim 1 in which a rack is provided and formsthe driving connection between said pinions, said pinions being engagedwith said rack and being slidable transversely of the length of saidrack.

3. A device as claimed in claim 1 in which a rotatable shaft is providedhaving a crown gear on each end thereof engaging with said pinions fordrivingly connecting the pinions.

4. A device as claimed in claim 1 in which said shafts are at an angleto each other end spaced from each other, and a rack is provided fordrivingly connecting said pinions, said pinions being engaged with saidrack for sliding movement transversely of the length of said rack, saidrack having two faces, one engaged with the pinion on the adjustingshaft and the other engaged with the pinion on the actuating shaft, andsaid lever having the end engaged with said actuating shaft at an acuteangle to the direction of the length of the actuating shaft.

5. A device as claimed in claim 4 and a stop pin engageable with thepinion on said adjusting shaft when said pinion is in the positionremote from said bobbin.

6. A device as claimed in claim 1 in which a rotatable shaft is providedhaving a crown gear on each end engaging with said pinions for drivinglyconnecting said pinions, said adjusting shaft and said actuating shaftbeing at an angle to each other, and said lever having the end engagingthe said other end of the actuating shaft bent at an angle to the end ofthe lever engaging the other end of said adjusting shaft, said lastmentioned angle being substantially equal to the angle at which saidactuating shaft is in relation to said adjusting shaft, and an aligningpin on said lever and an aligning ca m adapted to be rotatably mountedon the sewing machine in engagement with said aligning pin, saidaligning cam being adapted to be rotated in synchronism with saidbobbin, said aligning cam having a recess adapted to be aligned with thetensioning means on said bobbin, whereby said aligning pin is receivedin said recess only when said adjusting shaft is aligned wit-h thethread tensioning means.

References Cited in the file of this patent UNITED STATES PATENTS1,264,284 Denne Apr. 30, 1918 2,441,881 Potter et al Jan. 9, 19232,582,211 Turner Jan. 8, 1952 2,907,292 Schenkengel Oct. 6, 1959

